Is it generally better to not say the usernames of people that are joining my stream?

For context, I’m a new streamer and I usually average around 2-3 people per stream but I know those are my friends, however on occasion I get one or two people that pop in who I don’t know. Should I leave them be or give a little nod so they know I see them? I’m just not sure how to approach it seeing as I want my viewers to know I appreciate them dropping in and watching the stream, but I also know that some people just like to lurk and watch, and I have nothing against the people that do.